Dyeing polyacrylonitrile fibers with the aid of cuprous complexes



United States atent O DYEING POLYACRYLONITRILE FIBERS WITH THE AID FCUPROUS COMPLEXES No Drawing. Original application Sept. 14, 1953, Ser.No. 380,126. Divided and this application Jan. 4,

1955, Ser. No. 479,864

9 Claims. (Cl. 8-55) This invention relates to an improved process ofdyeing polyacrylonitrile fibers and more particularly an improved methodof dyeing polyacrylonitrile fibers by a modification of the cuprous ionmethod.

Most acid and direct dyes are not substantive to fibers of acrylonitrilepolymers. In order to overcome this drawback, it has been proposed todye in the presence of cuprous ions, the socalled cuprous ion method ofdyeing. While it has been possible by this means to effect satisfactorydyeings with acid and direct dyes, a number of ,difiiculties' havearisen.

When the cuprous ion is produced in the dye bath, for example, by thereaction of copper sulfate and reducing agents, it is not very stable insolution. As a result in neutral or alkaline media there is a tendencyfor cuprous oxide to precipitate, whereas in acid medium the cuprous ionmay disproportionate to free copper and cupric ion. in each case, theshade of the dyeing is affected and this usually results in acomparatively dull dyeing.

Another drawback lies in the tendency of the cuprous ion to be oxidizedby atmospheric oxygen to the cupric state. In order to prevent this,rather large excesses of reducing agent have been used which go farbeyond the stoichiometric amount required for the initial reduction ofthe copper sulfate. Reducing agents when used in excess add materiallyto the expense of the dyeing. An even more serious result is obtainedwith certain dyes which are not stable to the reducing agent present inlarge excess. These dyes are partly reduced, which again results in achange in shade or, even if the dyeing is not off shade, additional costis involved because the destroyed dyestufl? is wasted.

As a result a compromise has been necessary in choosing a reducing agentwhich causes the least damage and affects the fewest number of dyes. Inpractice the reducing-agent usually chosen is hydroxyl-ammonium sulfate.Unfortunately, this reducing agent is relatively expensive, adding stillfurther to the economic disadvantage of the cuprous ion dyeing method.

Another disadvantage of the ordinary cuprous ion method is unduly rapidexhaustion of the dye, especially when a large concentration of cuprousion is formed in solution. This excessive speed of exhaustion results insurface dyeing with poor penetration so that the final dyeing is notlevel, crocks badly, and does not build up to high strength for 'a givenuse of copper.

Proposals have been made to avoid or to minimize the disadvantages setout above by carrying out the reduction of the cupric sulfate to thecuprous ion at a strictly controlled rate so that there is never a highconcentration of free cuprous ion in solution. This controlledreduction, while theoretically possible, slows up dyeing and requiresunnecessarily critical control. Both these factors are economicallyundesirable.

According to the present invention, we have found that if the cuprouscopper is present in the form of a particular restrictive group ofcomplex ions the difliculties are avoided and the fibers ofpolyacryloniu'ile or its co- 2,939,759 Patented June 7, 1960 polymerscan be dyed deep, level shades with a maximum of reliability. No largeexcess of costly reducing agent is necessary, and the ordinary acid anddirect dyes are not adversely affected.

Not all complex cuprous copper ions can be used, for while it isdesirable to produce a sufficiently stable complex ion so thatoxidation, disproportionation and other difliculties are avoided in thedyebath, it is also necessary that the cuprous ion be suflicientlyreactive so that it will enter into the dyeing reaction. Thus, forexample, complex ions derived from thiourea and its derivatives,ammonia, inorgam'c cyanides, and thiosulfates, are completely useless asthey are so stable that the dye does not exhaust properly from the bathto the fiber.

We have found that only certain complexing agents are useful. Theseagents are organic compounds having at least one cyano group. A widerange of compounds is therefore useful and may contain other functionalgroups besides the cyano group. Illustrative compounds of this typewhich may be used include the lower aliphatic, dinitriles, such assuccinonitrile and glutaronitrile and oxygenated nitriles such asdicyanoethyl ether, beta-hydroxypropionitrile, glycolonitrile,lactonitrile, and beta-methoxypropionitrile. Also useful are cyanocompounds which contain additional nitrogen in the molecule, such ascyanoacetamide, beta-diethylaminopropionitrile andbis-cyanoethylcyanamide. Likewise other substituents may be present,such as halogen or sulfur, as beta-chloropropionitrile, andbeta-beta-thiodipropionitrile.

Particularly useful complexing agents are the cyanoguanidines such ascyanoguanidine itself, 1-alkyl-3-cyanoguanid'ines,1-phenyl-1-methyl-3-cyanoguanidine, 1-acetyl- 3-cyanaguanidine,1-carbalkoxy-3-cyanoguanidines, such as 1 carbethoxy 3 cyanoguanidine, 1carballyloxy- 3-cyanoguanidine, and the like.

In general, the anion to which the complex cuprous ion is united isunimportant, and any of the ordinary ions such as sulfate or nitrate maybe used. It is also possible to work with chlorides, but here it isnecessary to proceed with caution because if there is too much chlorideion present, more than one mol per mol of cuprous ion compound, thelatter may complex with the chloride ion itself instead of with thedesired complexing agent. In general, it is best to select the anion onthe basis of the solubility of the complex salt.

It is an advantage of the present invention that the method ofintroducing the complex cuprous ion into the dye bath is in no sensecritical. Thus, the complexing agent may be added to the dyebath beforeor during reduction of the copper sulfate, in which case the stablecomplex cuprous ion is formed in solution. Or the complex cuprous ionmay be formed as a soluble crystalline salt which can either be addeddirectly to the bath or can be blended with the dye powder itself. Thelatter two methods are preferred, as the dyeing procedure isconsiderably simplified since the dyer does not need to preform thereduction in the dye bath but adds a pre-formed complex salt in whichthe copper is already in the euprous state. The blend of complex cuprouscompound with the dyestuff itself is even simpler and presents theadditional advantage that a dyer can purchase dyes which can be usedwithout further treatment.

In every case, the present invention presents numerous advantages overthe ordinary cuprous ion dyeing methods. First, there is no strongreducing agent in the dyebath, and so there is no danger of destroyingany sensitive dyestuffs. The cuprous copper is present in the dyebath ina form in which it is relatively stable, and brighter and strongerdyeings are obtainable than with the ordinary method. The shades areoften very close to those obtained on natural fibers, and it is anadvantage of the invention that the dyeing procedure operatessuccessfully on natural fibers, both cellulosic and basic nitrogenous.This is often possible to obtain satisfactory union dyeings.

While the complex cuprous ion is relatively stable toward oxidation byair and theoretically no additional reducing agent is required, we havefound that it is sometimes advantageous to use a small amount of a mildreducing agent, such as a sulfite. This reducing agent is really usedmore as an anti-oxidant and need not be so active that it could reducesensitive dyes. If the dyeing is carried out in the absence of air, ase.g., under an atmosphere of nitrogen, there is no need for the additionof such an antioxidant. In large scale dyeing operations, especially inclosed equipment, where there is little or no access of air, theaddition of an antioxidant is unnecessary.

One of the advantages of the present invention is that the cuprous ionis released by the complex to the fiber only gradually so that betterpenetration of the dye into the fiber is obtained, with level dyeing andno crocking. It is also possible to build up stronger dyeings for agiven usage of copper than in the ordinary cuprous ion dyeing method.When the preferred modification in which the complex cuprous compound isblended with the dye is employed, it is also possible to adjustaccurately the amount of cuprous ion for each individual dye to giveoptimum results, and this adjustment requires no further effort on thepart of the dyer.

It is an advantage of the present invention that the improved resultsobtained do not require any material changes from the well-known aciddyeing procedures. On the other hand, pH is important as in the ordinaryprocess, and necessary pH adjustments can be made with the usualreagents. While the optimum pH will vary somewhat from one dye toanother, in general the dyebath should be acid, and the optimum pH willordinarily lie in a range from 2 to 6.

When the complex cuprous ion is to be added to the bath, this may beeffected in various ways; for example, the whole of the complex cuprousion may be added before any dye 'is added, or it may be added inportions while the fiber is being heated with a solution of the dye. Thebest method to use will depend on operating conditions, and it is anadvantage of the present invention that it presents great flexibility inthis regard.

It is a further advantage of the present invention that it is notlimited to any particular method of spinning the polyacrylonitrile fiberand is applicable to the various commercial fibers, either those spunfrom a. solution of the polymer in an organic solvent, such as thefibers sold by the Du Pont Company under their trade name of Orlon orfibers spun from aqueous cold thiocyanate solutions such as a fiberproduced by the American Cyanarnid Company and designated X-Sl. This isin marked distinction to certain processes of dyeing with vat dyes inwhich the nature of the spinning markedly affects the dyeability of thefiber.

In another modification of the invention improved results are obtainedby subjecting the polyacry-lonitrile fiber to a preliminary scouring inthe presence of a cationic agent which is an aliphatic amidopropylquaternary ammonium salt. These cationic agents are described in thepatent to Cook and Moss, No. 2,589,674. This is followed by the ordinarydyeing procedure with the aid of the cuprous complex salt as describedabove. It has been found that this modification permits using a muchsmaller quantity of the cuprous complex for obtaining a desired strengthof dye, which is a definite economic advantage.

The amount of the cuprous ion complex is not critical. Of'course, itcannot be used in minute amounts, and in general at least 0.25 part ofthe complex per part of dye is necessary. Larger amounts of complex maybe used, but in general excessive amounts of complex are not desirable,as they do not improve the resulting dyeing and merely add to the cost.

Some of the cuprous ion complexes which may be used in the presentprocess are also themselves new chemical compounds and in one aspect ofthe present invention are included as such. While, of course, thecuprous ion complexes which are new chemical compounds are notrestricted to any particular method by which they are prepared, there isincluded in a specific modification of the invention as improvedprocess. We have found that it is possible to effect the production ofthe cuprous ion complex by reducing cupric compounds such as cupricsulfate, acetate and the like in aqueous media in the presence of acomplexing agent and introducing a desired anion, if it is not alreadypresent, in the form of its sodium salt. This process presents a verydefinite advantage as it is possible to use a wide variety of reducingagents many of which are much milder than could be used in the dyebathin the old cuprous ion dyeing method. This not only gives a much widerchoice of reducing agents but also permits the use of relatively cheapreducing agents whereas in the old cuprous ion dyeing procedure it wasoften necessary to use relatively expensive reducing agents such ashydroxylamine and its derivatives. The reducing agents used include theordinary reducing agents such as sulfur dioxide, sodium bisulfite,hydroxylamine, sodium thiosulfate, glyoxal, furf'ural, sodiumformaldehyde sulfoxylate, and the like. Instead of reducing the :solublecupric compound in the presence of a complexing agent and permitting thecomplex salt to precipitate out, it is possible to use simple insolublecuprous compounds such as cuprous chloride, cuprous bromide, or cuprousoxide. These compounds are slurried in an acidulation aqueous medium inthe presence of a complexing agent and give the complex salt directly,or in the case of the cuprous oxide, the desired anion may be introducedin the form of its sodium salt. In general, it is desirable to usecomplex salts which are soluble in water at least at elevatedtemperatures, and with slight acidulation to prevent hydrolysis.

vThe direct and acid dyes which can be used in the present invention arecharacterized by the presence 'of a sulfonic group. Actually avariety'of organic compounds can be used, all containing a sulfonicgroup, including colorless ones, such as the alkylsulfonic acids, forexample, ethyl sulfonic acid, dodecyl sulfonic acid and the like, or andsulfonic acids such as those of benzene, toluene, naphthalene and thelike. Other compounds are colorless but fluorescent and are of use asoptical brighteners and the like. Typical of such compounds are4,4'-dibenzoyl aminostilbene-2,2-disulfonic acid, 4,4-bis(2-methoxyben-By far the most important class of direct and acid dyes I are azo dyesof which the following are typicalexamp'les, the naming of which is bythe conventional method "in which a dashed arrow indicates diazotizingand coupling:

Sulfanilic acid- Znaphthol (Color Index'15l) naphthionic acid--2-nap11th0l-6,8-disulionic acld.(Co1or.Index N aphthionic acid----2-naphthol-6,8-disulfonic acid (Color Index 185) Naphthionicacidl-naphtholi-sulfonic acid (Color Index 179)Aminoazobenzene-d-sulionic acid- Z-naphthol (Color Index 275) Chromedyes such as: 1-arnino-2-naphthol-i-sulfonic acld---+ 2- naphthol (ColorIndex 202) Direct dyes such as:

Ethylated '2-naphthol-6,8-disulionic acid -bcnzidine-- .pheno (ColorIndex 382) Di5BIl$SiC1iHeIIIZ (s-arnino-lnaphthol-Gfldisulfonlc acid),(Colorludex Salicylic acid -benzidine- (resorclnol 4- -2-amlnophen'ol=4sulfonic acid, copperized)lqirgglgo-z-bromo-t(Z-suIfo-i-methylanilino)anthraquinone (Color Index-1,igifmmo-i,8-dihydroxyanthraquinone-3,7-disulfonic acid (Color Index1,4-bls-(2-sulfo-4-methylanilino)anthraquinone (Color Index 1078)quinoline dyes such as Quinoline Yellow (Color Index 801), which is asulfonated mixture of 2-quinolylindandione and .Z-quinaldylene,phthalide, thiazole dyes such as Direct Fast Yellow (Color Index 814)which is an oxidation product of dehydrothioparatoluidine sulfonic acidand Primuline (Color Index 812) which is a mixture of the sulfonic acidsof highly thionated dehydrothioparatoluidine anddehydrothioparatoluidine, stilbene dyes such as Direct Yellow R (ColorIndex 620) which is principally azoxyazodistilbene tetrasulfonic acid,and azinc dyes such as Wool Fast Blue (Color Index 833) which issulfonated dialkylaminophenylamino-phenylnaphthophenazonium chloride.

' As" has been pointed out above in the preferred modification of thepresent invention in which the complex cuprous compound is mixed orblended with the dyestutf, it is sometimes desirable to incorporate acertain amount of reducing agent. This is not for the purpose ofproducing the cuprous ion itself which is present in its preformed statebut may be needed in small amounts as an antioxida-nt. For instance,most samples of water contain dissolved air, and it is desirable toprevent any oxidation while the transfer of the cuprous ion is takingplace to the fiber. The reducing agents include the following:hydroxylamine salts, sodium or zinc formaldehyde sulfoxylate, sodiumbisulfite, and sodium dihydrogen hypophosphite. Where the dyeing isefiected in the absence of air, of course the reducing agent is notnecessary, and in general, the efiect of dissolved air is not veryserious in large-scale dyebaths.

The invention will be illustrated in the following specific examples inwhich the parts are by weight unless otherwise specified.

The first 8 examples relate to the production of cuprous ion complexeswhich are in themselves new chemical compounds; the remainingexamplesdealing with processes of dyeing, utilizing the cuprous ion complexes inthe present invention.

EXAMPLE 1 cuprous dicyandiamide sulfate To a solution of 10 parts cupricacetate monohydrate containing 7 parts acetic acid in 250 parts water isadded a solution of 13 parts dicyandiamide in 100 parts water, and themixture warmed to about 60 C. Then 4.75 parts sodium bisulfite is addedportionwise, the blue solution is immediately decolorized and a thickwhite precipitate appears. This is filtered off at room temperature,washed with water, and dried in vacuo; 13.3 parts fine white powder; Theproduct gives a positive test for cuprous copper, and for sulfate ion. Aportion recrystallized from very dilute sulfuric acid is shown byelementary analysis tobe [C1l(C2H N4)2]2 SO4- EXAMPLE 2 cuprousbis-dicyandiamide nitrate A solution of 25 parts cupric sulfatepentahydrate, 25.5 parts dicyandiamide, and '127 parts sodium nitrate in500 parts water is treated at 95 C. with 9.4 parts sodium bisulfiteadded portionwise until the blue color of the solution is almostentirely discharged, and a heavy white precipitate is formed. Themixture is cooled to room temperature, the precipitate is filtered off,and washed with 6 water, then dried in air. The product is soluble inwater on warming, gives a negative test for sulfate ion, a very fainttest for cupric copper, and a strong: test for cuprous copper.

A portion recrystallized from water slightly acidulated with nitric acidhas an elementary analysis corresponding to Cl1(C H4N4) NO3.

In the above example, for the sodium bisulfite one may substitute 8.25parts hydroxylammonium sulfate as the reducing agent.

EXAMPLE 3 Cuprous bis-dicyandiamide nitrate To a solution of 10 partscupric acetate monohydrate, 33.6 parts dicyandiamide, and 7 parts aceticacid in 200 parts water is added 5 parts copper powder, and the mixtureis heated at the boil until the blue color of the solution is virtuallydischarged. The hot solution is clarified to remove unreacted copper,and to the filtrate is added 25 parts sodium nitrate crystals. A thickwhite slurry is obtained, which is filtered at room temperature. Thewhite crystalline residue is washed with water, and has the sameproperties as the product of the previous example.

EXAMPLE 4 Cuprous dicyandiamide chloride To a solution of 20 partscupric acetate monohydrate, 33.6 parts dicyandiamide, and 7 parts aceticacid in 200 parts water maintained above C. is added portionwise overten minutes 7 parts hydroxylammoniurn chloride. The solution is heatedtill the evolution of gas practically ceases, and its color becomes apale yellow green. The complex salt, cuprous dicyandiamide chloride,begins to precipitate from the hot solution, and precipitation iscompleted by stirring to room temperature. The white needles arefiltered off, washed with water containing a small amount of aceticacid, and dried in vacuo.. A portion is recrystallized from hot wateracidulated with acetic acid, wherepon its elementary analysis shows itto be Cu(C H N )Cl.

In the above example instead of hydroxylammonium chloride one may use asthe reducing agent 9.4 parts sodium bisulfite, adding also 30 partssodium chloride crystals to furnish chloride ion.

EXAMPLE 5 Cuprous dicyandiamide chloride Into 200 parts water acidulatedwith 5 parts acetic acid is stirred'S parts cuprous chloride, and theslurry heated above 70 C. Then 8.6 parts dicyandiamide dissolved in 75parts water is added, and the mixture heated to the boil with stirringtill a complete solution is obtained. On cooling, the white needles ofcuprous dicyandiamide chloride precipitate and are obtained byfiltration.

EXAMPLE 6 Cuprous di-glutaronitrile nitrate To a solution of 8.33 partscopper sulfate pentahyd'rate, 12.5 parts glutaronitrile, and 5.5 partssodium nitrate in 175 parts water is added at C. 3.13 parts sodiumbisulfite gradually in portions. solution is virtually discharged, themixture is cooled to room temperature, and the thick white precipitateis filtered off, washed with very dilute nitric acid, and dried in avacuum. If further purification is desired, the product may berecrystallized from very dilute nitric acid. Elementary analysis thencorresponds to the formula Cu(C H N NO t In the above example in placeof sodium bisulfitc one may use as the reducing agent 2.75 partshydroxylammonium sulfate added as a solutionin water.

When the color of the also about equal.

EXAMPLE 7 Cuprous bis-'(bis cyanethyl ether) nitrate A solution of 12.5parts copper sulfate pentahydrate in 250 parts water is reduced with 4.7parts .sodium bisulfite added portionwise .at about 95 C. in thepresence of 24.8 parts bis-cyanoethyl ether. The addition of 4.25 partssodium nitrate gives a precipitate of white needles which is filteredoff at 10 C., washed with very dilute acetic acid and dried in a vacuum.Recrystallization from very dilute acetic acid gives a pure productwhose elementary analysis corresponds to the formula Cl1(C5HgON2) 2N03.

In the above example for the reducing agent one may use 4.1 partshydroxylammonium sulfate.

EXAMPLE 8 Cuprous cyanoacetamide chloride A hot solution of '25 partscopper sulfate pentahydrate in 400 parts water is reduced with 8.8 partshydroxylammonium sulfate in the presence of 33.6 parts cyanoacctamide.After heating to 95 C., 5.8 parts sodium chloride is added, the solutionis cooled, and the white crystalline precipitate is filtered off, washedwith dilute acetic acid, and dried in a vacuum. The product gives a testfor cuprous copper and for chloride ion, and may be recrystallized fromdilute acetic acid.

EXAMPLE 9 Five parts of polyacrylonitrile fiber spun from cold aqueousthiolcyanate solution as described in the 'U.S. Patent No. 2,558,730(Cresswell to American Cyanarnid Co.) are entered in the form of a skeininto 150 parts of water. There are added solutions of 0.05 part of thedye of Color Index 185, to 0.2 part of sulfuric acid and 0.375 part ofthe product of Example 2, which is added in .the form of a 0.5% solutionprepared by warming in water at 180 F. The amounts of the variouscomponents calculated on the weight of the fiber amounts to 1% dye, 4%sulfuric acid and 7.5% of the cuprous complex salt. The dye bath isheated to 200 F., a clear solution resulting, and is maintained at thistemperature until dyeing is complete. Complete exhaustion of the dyefrom the liquor has occurred, whereupon the skein is removed, rinsed anddried. The skein shows a bright scarlet shade, which shows littledifference from the shade of the same dye when applied to wool from anacid bath. The strength of color on the two fibers is The dyeing onpolyacrylonitrile is distinguished by its brightness, levelness, andexcellent fastness to crocking.

When the same dye is applied to the polyacrylonitrile by the ordinarycuprous ion method, copper sulfate pen'tahydrate is required forcomplete exhaust, together with 2.5% hydroxylammonium sulfate forreduction. .Such a procedure shows noticeable disadvantages comparedwith the procedure of the first paragraph, such as scumming in the dyebath, a pronounced shade difference from the color on wool,discoloration of the polyacrylonitrile fiber, dull shade, unevendyeings, and a marked tendency to crock.

The above procedure is followed, using the same amount of dye but withdifferent amounts of the cuprous complex salt. When the amount of thecuprous complex 'salt is from 0.5% to 1.2%, pastel shades are obtained.When the dyeing procedure is followed using 7.5% of the cuprous complexsalt, the amount of dye can be increased to from 2 to 5%. Completeexhaustion of the 'dye is still maintained and the strength builds upproportionate to'the amount of dye added. Both with the pastel shadesand with the very heavy shades the same desirable qualities ofbrightness, levelness and excellent fastness 'to crock'ing are achieved.

above dyeing procedures are equally applicable to union dyeing where-thepolyacrylonitrile fiber is combined with wool. The same bright, level,fast shades are obtained on both fibers.

dye Cl. 185 with dyes Cl. 202, 235, 275, 801, or 1088 or with theprototype dyes numbers 146 and 326, the results obtained are the samequality.

EXAMPLE 10 A dye bath is made up with a five part skein of thiocyanatespun polyacrylonitrile fiber immersed in 150 parts of water to which areadded solutions of 0.05 part of the direct dye of C11. 346, 0.2 part ofsulfuric acid, and 0.075 part of the nitrate of the cuprous complex ofdicyandiamide (the product of Example 2, added'as a 0.5% solution).Calculate-d on the weight of the fiber, the various additions are 1%dye, 4% sulfuric acid, and 1.5% of. the complex cuprous salt. The bathis heated to 200 F., giving a clear solution, and held at 200 F. untildyeing is complete; the skein is removed, rinsed and dried. 'There isobtained a yellow dyeing on the fiber full-y equalin hue, brightness,and strength to that ohtainable on cotton; the dyeing'is also uniformand resistant to .crocking. 'In' contrast, when this dye is applied topolyacrylonitrile by the conventional cuprous ion methods, from coppersulfate reduced in the bath with hydroxylarnmonium sulfate, there isobserved a precipitation in the dye bath, and the dyeing is duller, lesseven, susceptible to crocking, and shows a marked shade difference ascompared with the color on cotton.

The procedure of the above example is repeated with a union .of thepolyacrylonitrile fiber with cotton or rayon. Both fibers are dyedsmoothly. Replacing the cuprous complex salt of Example 2 with thecomplexes of the other examples gives the same dyeing results.

When the dye Cl. 346 is replaced with dye CJI. 349a, 365 or prototypes47, 71, 72, the .same quality of dyeing results.

EXAMPLE 11 bath is heated at 200 F. until dyeing is complete, and

the skein removed, rinsed, and dried. There is obtained complete exhaustof the bath and the dyeing has fully the strength observed in Example 9,where more .of the complex cuprous salt was used. When the .dye isapplied by the ordinary cuprous ion method, using an equal amount ofcopper, that is, 0.05 part copper sulfate pentahydnate reduced in thebath with 0.025 part hydroxylanrmonium sulfate, there is obtained onlyexhaust of the dye liquor. Moreover, the same undesirable properties.are observed as those described in Example 9 while the dyeing madeusing the complexed cuprous salt has the same advantages.

When the procedure of the above example is carried out substituting thehydroxylamrnonium sulfate with an equal quantity of sodium dihydrogenhypophosphite or sodium formaldehyde sulfoxylate, the results obtainedare the same.

EXAMPLE 12 Five parts of a skein of thiocyanate spun polyacrylonitri-lefiber is added to a dye'bath composed of parts of water containing 0.05part of the dye prototype 144, 0.12 part of the product of the Example 2and 0.045 part of sodium "bisulfite. The bath is heated to 200 F. and

v maintained at this temperature until dyeing is nearly complete,whereupon 0.1 part sulfuric is added and the bath maintained at the sametemperature until the exhaustion is complete and the full strength ofcolor is developed on the fiber. This color strength is equal to thatobtained with the same amount of dye on wool.

EXAMPLE 13 Five parts of a skein of thiocyanate spun polyacrylonitri-lefiber is added to a dye bath composed of 150 parts of water, 0.05 partof the dye CJI. 814, 0.07 part of the product of Example 2, 0.0125 partsodium bisulfite, 0.05 part ammonium hydroxide and 0.5 part ammoniumchloride. The bath is heated to 200 F. and is maintained until acomplete exhaust results. The strength of dyeing is equal to thatobtained on cotton.

EXAMPLE 14 A blend is prepared by thoroughly mixing in solid form 35parts of the dye CJI. 185 with 65 parts of the product of Example 2. Asolution of 0.14 part of this blend is made :by warming in 30 parts ofwater at 180 F. This solution is added to a dye bath containing 5 partsof a skein of thiocyanate spun polyacrylonitrile fiber, 15 parts ofwater and 0.2 part sulfuric acid. The dye bath is heated to 200 F. andmaintained until exhaust is complete. Thereupon, the fiber is removed,rinsed and dried. It is dyed a bright scarletshade equal in hue,strength and fastness to that obtained by the procedure of Example 9. l

The procedureof the example is followed using different cuprous complexsalts, namely, products of Examples 1, 4, 6, 7, and the results are thesame. When a blend isprepared of 35 parts of a dye Cl. 185, 55 parts ofthe product of Example 2 and ten parts of sodium bisulfite, a verystable blend is obtained which keeps well, and which, when added to adye bath as described above, produces the same shade. Same results areobtained when the sodium bisulfite is replaced by an equal amount ofeither hydroxylammonium sulfate, sodium dihydrogen hypophosphite,imonohydrate or sodium form aldehyde sulfoxylate.

EXAMPLE 15 A blend is prepared by thoroughly mixing in solid form 75parts of the dye Cl. 346 with 25 parts of the product of Example 2. Asolution is prepared by wanning 0.067 part of the blend in 20 parts ofwater to 180 F. This solution is added to a dye bath containing 5 partsof a skein of thiocyanate spun polyacrylonitrile fiber, 150 parts ofwater, and 0.2 part sulfuric acid. The bath is heated to 200 and ismaintained until exhaustion is substantially complete. A bright yellowdyeing is obtained which is equal in shade, strength, and fastness tothat obtained by the procedure of Example 10. I

A blend is also prepared substituting 20 parts of the product of Example2 and 5 parts of sodium bisulfite for 25 parts of the cuprous complexsalt. The blend keeps well. When added to a dyebat-h as described above,it produces the same results. A product of the same characteristics isobtained if the sodium bisulfite is substituted by hydroxylammoniumsulfate, sodium dihydrogen hypophosphite rnonohyd'rate or sodiumformaldehyde sulfoxylate.

EXAMPLE 16 To 150 parts of water at 180 F. is added successively 0.1part sulfuric acid a solution of 0.25 part of copper sulfatepentahydrate, a solution of 0.25 part dicyandiamide, 5 parts ofthiocyanate spun polyacrylonitrile fiber, a solution of 0.25 part sodiumbisulfite and a solution of 0.05 part of the dye Cl. 185. The bath isheated at 200 F. and maintained until exhaustion is complete. The dyedskein is removed, rinsed, and dried and shows sub- 10 stantia'lly thesame strength, shade and fastness as the skein dyed by the procedure ofExample 9.

EXAMPLE 17 Five parts of a skein of dry spun polyacrylonitrile sold bythe Du Pont Company under the trade name of Orlon 41 is dyed in a dyebath containing 150 parts of water, 0.05 part of dyeC.I. 304, 0.07 partof the product of Example 2, 0.0125 part sodium bisulfite, 0.25 partammonium chloride and 0.1 part sulfuric acid. The bath is heated to 200F. until substantial exhaust of the dye bath is noted. The skein isremoved, rinsed, and dried and is dyed a pastel shade. The shade is muchbrighter and more uniform than when the same material is dyed by theordinary cuprous ion method using an equal amount of copper, that is tosay, 0.05 part copper sulfate pentahydrate reduced in the bath with0.025 part hydroxylammonium sulfate.

EXAMPLE 18 Five parts of a skein of acrylonitrile copolymer sold byUnion Carbide and Carbon under the trade name Dynel is dyed in a bathcontaining 0.25 part of the product of Example 4, 0.1 part sulfuric acidand 0.05 part of the dye Cl. 179. i The bath is heated to 200 F. untilconsiderable exhaust of dye from the bath is noted. The fiber is rinsed,dried, and shows a good strength of dyeing. In the absence of thecuprous complex a very weak tint only is obtained.

EXAMPLE 19 Five parts of a skein of-a fiber which is a copolymer ofacrylonitrile with a small amount of a vinyl pyridine and sold by theChemstrand Corporation under the trade name Acrilan is dyed in the bathcontaining 0.25 part of the product of Example 4, 0.1 part sulfuric acidand 0.05 part of the dye Cl. 179. The bath is heated to 200 F. untilthere is a substantial exhaust of the dye. 'Ihe skein isthen rinsed anddried and shows a good strength of dyeing. When compared with a blankhaving no cuprous complex the exhaust is much better and the color onthe fiber is much stronger.

EXAMPLE 20 To a slurry of 2.31 parts of l-carballyloxy-B-cyanoguanidinein 250 parts water containing a small amount of acetic acid was added 10parts of a solution containing 1.2 parts copper sulfate pentahydrate.The mixture was heatedto C. Then 0.5 part sodium bisulfite was graduallyadded as a solution. The blue color disappeared and a new precipitatewas formed. After further heating at 100 C., the product was isolated byfiltration, washed with water, and dried in vacuo. A white powder wasobtained which gave a test for cuprous copper with an o-phenanthrolinereagent, and a negative test for cupric copper. When added to a dye bathin an amount equal to 5% of the weight of the fiber, together with 1% ofthe dye of Cl. 179, and 2% sulfuric acid, it gave virtually completeexhaust on a skein of thiocyanate spun polyacrylonitrile fiber. Similarresults were obtained by using the dye of 0.1. 1088. i r 4 EXAMPLE 21 Toa solution of 2.00 parts of 1-t-butyl-3-cyanoguanidine in 250 parts ofwater acidulated with acetic acid was added one part of copper acetatemonohydrate. The solution was treated portionwise with 0.5 part sodiumbisulfite at 100 C. The product was isolated by filtration, washed withvery dilute sulfuric acid, and dried. It gave a positive test forcuprous copper, and when added to a dyebath acidified with sulfuricacid, it promoted the dyeing of thiocyanate spun polyacrylonitrile fiberwith the dyes of C1. 179 or 1088.

The same results were obtained when in the above procedure instead of1-t-butyl-3-cyanoguanidine there was used. 1-pheny1-3-cyanoguanidine,1-p-chlorophenyl-3-cy anoguanidine, or1-methyl-1-phcnyl-3-cyanoguanidine.

EXAMPLE 22 To a hot solution containing 1.76 parts of 1-acetyl-3-cyanoguanidine, one part of copper acetate monohydra-te, and a smallamount of acetic acid in 250 parts of water, Was added gradually 0.5part sodium bisulfite at 100 C. The white precipitate was isolated byfiltration, washed with very dilute sulfuric acid, and dried .in vacuo.The product was soluble in hot aqueous medium, gave a test for .cuprouscopper, and promoted the dyeing of spun polyacrylonitrile fiber from abath acidified with sulfuric acid by means of the dye of Cl. 179 or1088.

EXAMPLE 23 To a solution of 12.5 parts of copper sulfate pentahydrate in150 parts of water was added a solution of 22.8 parts ofmonomethyloldicyandiamide in 100 parts of water. 4.1 parts ofcrystalline hydroxylammonium sulfate were added gradually at 95 9 C.After the evolution of gas had ceased, 4.2 parts of sodium nitratecrystals were added, and the mixture was cooled. The precipitate wasfiltered off, and purified by recrystallization from hot wateracidulated with nitric acid. The white crystalline product was recoveredby filtration' and washed with alcohol. It gave a positive test for.cuprous copper with o-phenanthroline. When 5.5% of the product, on theweight of the fiber, was added to a dye bath containing 1% of the dye ofCJI, 179, and 2% sulfuric acid, there was obtained complete exhaustionof the dye on five parts of a skein of thiocyanate spunpolyacrylonitrile fiber.

EXAMPLE 24 A solution is prepared of 0.1 part of 50% stock of thecationic agent, stearamidopropyl-dimethyl-hydroxyethylammonium chloride,and 0.1 part by volume of concent-rated ammonia in l50parts of water.Five parts of a skein. of thiocyanate spun polyacrylonitrile fiber arescoured by heating in this solution at 160 F. for minutes, after whichthe skein is removed and rinsed. It is then entered into a bathcontaining 0.07 part of the acid dye of Cl. 235, 0.025 part of theproduct of Example 2, and 0.25 part of ammonium chloride, in 150 partsof wa ter, and dyed at 200 F. for one-half hour. Then 0.1 part sulfuricacid is added and the dyeing is continued at 200 F. until exhaustion isvirtually complete. The skein is removed, rinsed, and dried. It has afull strength of dyeing equal in quality to that of Example 9 eventhough much less of the complex cuprous salt was used than in thatexample.

When the same procedures are used with other acid dyes, Cl. 430, 801,1078, 1088 and Prototype No. 143, or with direct dyes Cl. 346, 349a and653 the strong dyeings are obtained.

This application is a division of our copending application Serial No.380,126, filed September 14, 1953.

We claim:

1. A particulate blended dyestufi composition comprising: a blend of onehundred parts by weight of an organic dyestuft containing at least onesulfonate radical in its structure, and at least 25 parts by weight of acuprous complex salt of an organic compound, said organic compound beingselected from the group consisting of the lower aliphatic dinitriles andoxygenated nitriles, Bfl-dicyanoethyl ether, cyanamide and itsdi(lower-alkyl) and di(cyano lower alkyl) derivatives, cyanoacetamide,cyanoguanidine and substituted ,cyanoguanidines, said composition beingsoluble in aqueous acid solution atra pH of from about two to about sixto form a dyebath adapted for the dyeing of polyacrylonitrile fibers.

2. A blend according to claim 1 in which in said dyestuff thechromophoric grouping is an azoradical.

3. A blend according to claim 1 in which in said dyestufl thechromophoric grouping is an anthraquinone radical.

4. A blend according to claim 1 in which said blend also contains asmall amount of a reducing agent.

5. A blend according to claim 4 in which said reducing agent is sodiumbisulfite.

6. A process of dyeing polyacrylonitrile fibers which comprises: formingan aqueous acid dyebath containing one hundred parts by weight of anorganic dyestuif containing at least one sulfonate radical in itsstructure, and at least 25- parts by weight of a cuprous complex salt ofan organic compound, said organic compound being selected from the groupconsisting of the lower aliphatic dinitriles and oxygenated nitriles,fl,i3'- dicyanoethyl ether, cyanarnide and its di(lower-alkyl) anddi(cyano lower alkyl) derivatives, cyanoacetamide, cyanoguanidineandsubstituted cyanoguanidines, said dyebath having a pH in the range fromabout two to about six; subjectingrsaid fibers to the action of saiddyebath; whereby exhaustion of the dye is initiated; and continuing saidaction until exhaustion of the dye on said fibers substantially ceases.

7. A process according to claim 6 in which said dye is an azo dye.

8. A process according to claim 6 in which said complex is a cuprouscomplex salt with dicyandiamide.

9. A process according to claim 6 in which the fiber is pretreated withan aliphatic amidopropyl quaternany salt.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Morgan: 1 our. Chem. Soc., vol. 123, 2901-2907.

Blaker: The Copper Method for Dyeing Orlon Acrylic Fiber, Am. DyestuifRep., Jan. 21, 1952, p. 39.

Meunier, P. L.: New Developments in the Dyeing of Orlon Acrylic Fiber,Am. wDyestuff Rep., July 20, 1953, p. 470.

Bailar: Chemistry of the Coordination Compounds, Reinhold Pub. Co.,N.Y., 1956, p. 407.

tr m inline 33, for "3-cyanaguanidine" read 3-eyanoguanidine UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION ZPatent No. 2,939,759June 7, 1960 Mario Scalera et a1.

Column 2, lines 26 and 27, strike out "beta-diethylamino- Ipropionitrileand bis-cyanoethylcyanamide." and insert instead cyanamide, dialklcyanamides and bis-cyanoethylcyanamide. i Y 5 l fcolumn 9, lines 32 and33, Example 14, for "Examples 1 4, 6, 7, end the results are the same."read Examples 1, 4, 6 7, and 8. The results are the same.

Signed and sealed this 1st day of November 1960.

(SEAL) fittest:

KARL H. AXLINE ROBERT C. WATSON Questing Ofiicer Commissioner of Patents

1. A PARTICULATE BLENDED DYESTUFF COMPOSITION COMPRISING: A BLEND OF ONEHUNDRED PARTS BY WEIGHT OF AN ORGANIC DYESTUFF CONTAINING AT LEAST ONESULFONATE RADICAL IN ITS STRUCTURE, AND AT LEST 25 PARTS BY WEIGHT OFCUPROUS COMPLEX SALT OF AN ORGANIC COMPOUND, SAID ORGANIC COMPOUND BEINGSELECTED FROM THE GROUP CONSISTING OF THE LOWER ALIPHATIC DINITRILES ANDOXYGENATED NITRILES, B,B''-DICYANOETHYL ETHER, CYANAMIDE AND ITSDI(LOWER-ALKYL) AND DI(CYANO LOWER ALKYL) DERIVATIVES, CYANOACETAMIDE,CYANOGUANIDINE AND SUBSTITUTED CYANOGUANIDINES, SAID COMPOSITION BEINGSOLUBLE IN AQUEOUS ACID SOLUTION AT A PH OF FROM ABOUT TWO TO ABOUT SIXTO FORM A DYEBATH ADAPTED FOR THE DYEING OF POLYACRYLONITRILE FIBERS. 6.A PROCESS OF DYEING POLYACRYLONITRILE FIBERS WHICH COMPRISES: FORMING ANAQUEOUS ACID DYEBATH CONONE HUNDRED PARTS BY WEIGHT OF AN ORGANICDYESTUFF CONTAINING AT LEAST ONE SULFONATE RADICAL IN ITS STRUCTURE, ANDAT LEAST 25 PARTS BY WEIGHT OF AN CUPROUS COMPLEX SALT OF AN ORGANICCOMPOUND, SAID ORGANIC COMPOUND BEING SELECTED FROM THE GROUP CONSISTINGOF THE LOWER ALIPHATIC DINITRILES AND OXYGENATED NITRILES,B,B''-DICYANOETHYL ETHER, CYANAMIDE AND ITS DI(LOWER-ALKYL) AND DI(CYANOLOWER ALKYL) DERIVATIVES, CYANOACETAMIDE, CYANOGUANIDINE AND SUBSTITUTEDCYANOGUANIDINES, SAID DYEBATH HAVING A PH IN THE RANGE FROM ABOUT TWO TOABOUT SIX, SUBJECTING SAID FIBERS TO THE ACTION OF SAID DYEBATH, WHEREBYEXHAUSTION OF THE DYE IS INITIATED, AND CONTINUING SAID ACTION UNTILEXHAUSTION OF THE DYE ON SAID FIBERS SUBSTANTIALLY CEASES.